Here's a really good link. I'm not sure what to use because I've always had CalMag but hopefully you can find out whether epsom salts is ok to use here.

International Cannagraphic Magazine Forums - The Complete guide to Sick Plants,pH, and Pest troubles!
Weedhound Reviewed by Weedhound on . I'm trying to defy the odds...but My friend found some really good "dro" there was a couple of seeds in it,she decided to throw them in some dirt,a week later she was amazed because they started to grow,She gave me 3 plants,one died.I grew hydro before and I noticed a very fast growth rate compared to soil,I took the plants out of the dirt and I transplanted them to my bubbler,in the meantime I sprouted 7 other seeds that I had.Now I have nine plants in a 3 gallon bubbler(the plants that she gave me are about 4 weeks,my Rating: 5